Fluorine-Doped Carbon Particles Derived from Lotus Petioles as High-Performance Anode Materials for Sodium-Ion Batteries

In contrast to the extensive investigation of the electrochemical performance of conventional carbon materials in sodium-ion batteries, there has been scarcely any study of sodium storage property of fluorine-doped carbon. Here we report for the first time the application of fluorine-doped carbon particles (F-CP) synthesized through pyrolysis of lotus petioles as anode materials for sodium-ion batteries. Electrochemical tests demonstrate that the F-CP electrode delivers an initial charge capacity of 230 mA h g^-1 at a current density of 50 mA g^-1 between 0.001 and 2.8 V, which greatly outperforms the corresponding value of 149 mA h g^-1 for the counterpart banana peels-derived carbon (BPC). Even under 200 mA g^-1, the F-CP electrode could still exhibit a charge capacity of 228 mA h g^-1 with initial charge capacity retention of 99.1% after 200 cycles compared to the BPC electrode with 107 mA h g^-1 and 71.8%. The F-doping and the large interlayer distance as well as the disorder structure contribute to a lowering of the sodium ion insertion-extraction barrier, thus promoting the Na⁺ diffusion and providing more active sites for Na⁺ storage. In specific, the F-CP electrode shows longer low-discharge-plateau and better kinetics than does the common carbon-based electrode. The unique electrochemical performance of F-CP enriches the existing knowledge of the carbon-based electrode materials and broadens avenues for rational design of anode materials in sodium-ion batteries.